A general solution is developed to calculate foundation heat transfer for a slab-on-grade floor with lifted ground. The Interzone Temperature Profile Estimation (ITPE) technique is applied to determine the steady state variation of temperature within the ground. A water table at constant temperature is assumed to exist at a given depth below the soil surface. The derived solution addresses all the common horizontal insulation configurations for slab-on-grade floor foundations. The effect of various insulation configurations and the height of the lifted ground on foundation heat loss are discussed in detail.